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[James Montebello]

> I just wondered why I haven't seen any electronic pressure regulators
> under PW control.  Automotive fuel pumps seem like a great place for
> variables to accumulate, machined solenoids seem more accurate.  If
> fuel injectors can be made, something similar should be possible as an
> inline valve.  So why make circuits to control high current pump
> rather than inline valve?  

They have been.  The Bosch CIS with Lambda system used a plain-jane
injector has an electronically controllable inline pressure regulator.
Used in several European cars in the 80s (VW, Porsche, and Volvo, to
name three). 

On the subject of dynamic fuel pressure regulators, the Digifant system 
used by VW in the late 80s had a vacuum-controlled pressure regulator 
that was simply plumbed directly to the intake manifold.  I suppose it 
would be possible to have this do most load compensation, and only vary 
PW by temperature and switches for fully-closed and fully-open throttle.  
Dunno if Digifant did this or not, but it sounds like just the kind of
thing the Germans would do.

james montebello